Use of oxalic acid to remove stains

[Andres Escalante]

Good day everyone. Has anyone used oxalic acid to remove stains from maple necks? It is sold in crystals and I don't know how to use it. All I know is I must wear gloves. Thanks for all input.

[Charlie Schultz]

Hi Andres,
I've not used oxalic acid on maple. I've used it on cat pee on unfinished red oak and it did get the stain out, thought it seemed to lighten the surrounding wood a little (but after the finish was on, it was not noticeable at all). I also tried it on spruce (stains from wet rosette sticks), it helped but not enough. I take it the stain is too deep to be sanded or scraped out? Try it on a scrap of maple to see how it affects the maple? As for mixing it, hopefully the package includes instructions?

[Mark Swanson]

I have used the stuff when it was sold as rust remover in a spray bottle from an auto parts store. I have no idea what the concentration was, but it worked great when removing metal stains that my side bender left in the wood. The stains could not be sanded out, they seemed to be right through the wood. I squirted the stuff on, and let it dry and as it dried the stains would flat out disappear. It was amazing how well it works on these metal-type stains, I suspect that it won't work as ell on other types of stain.

[Michael Lewis]

Oxalic acid has been sold as a bleach for wood. As Charlie suggested, you should have some directions to use that stuff. I used to have some but I don't remember what I thought I needed it for.

[Steve Senseney]

Rhubarb has oxalic acid.

If you have some scrap wood to test, you might consider trying the rhubarb.

[Michael Jennings]

" Bee-bop-a-ree-bop, rhubarb pie". Who'd a thunk it? !!

Mj

[Andres Escalante]

Thanks for the input. I prepared a concentrate solution and applied some drops in some small stains to check. After letting it dry for about 15 minutes, the stains were gone. It worked way better than regular bleach (chlorine). One thing that surprised me, it didn't harm the surrounding finish, although I have to refinish the neck. The wood lightened a bit mote than the surrounding wood but it must be due to the surrounding finish; nothing to worry about. I should post some before and after pictures.

[Michael Jennings]

Sorry for the tongue in cheek remark above, but I just happened to be listening to "Prairie Home Companion" when I came across Steve's comment. MJ

[Clay Schaeffer]

Hi Michael,
I liked your comment. If we can't have a little fun, this place would get pretty boring.